The present invention relates generally to treating diseased bone by removing tissue from within the bone and more particularly, by immediately removing neoplastic and osteoporotic tissue using a minimally invasive electrosurgical probe. The present invention is particularly well suited for the treatment of the vertebrae as well as other bone bodies such as, for example, the femur.
Vertebroplasty is a minimally invasive percutaneous approach to treat vertebral compression fractures (VCFs). VCFs may be secondary to osteoporosis or to the presence of (and treatment) of a tumor in the vertebrae (e.g., myelomas or metastatic tumors).
Vertebroplasty involves injecting a viscous solution of bone cement (e.g., poly-methylmethacrylate) into the fractured vertebral body. The cement fills the spaces between the bone fragments and serves to stabilize the vertebral body, preventing spinal collapse. The viscous solution may include a radio-opaque material to provide fluoroscopic guidance for the physician. See, for example, U.S. Pat. Nos. 6,348,055 and 6,138,190 both issued to Preissman, describing a system for delivery of implant material to a desired site. Each patent and patent application mentioned in this patent application is hereby incorporated by reference in its entirety.
A problem with vertebroplasty procedures is the small space available within the vertebral body that may be filled with the bone cement. Small spaces in the vertebral body are generally undesirable because only a small volume of stabilizing bone cement may be added to the space. In contrast, a large space may accept a large amount of bone cement, tending to increase the life of the semi-artificial bone body.
Another problem with vertebroplasty is providing a solid surface for the bone cement to adhere. Providing a solid smooth surface for the cement to adhere to is not trivial because osteoporotic bone often consists of a multitude of bone fragments in a haphazard arrangement. Accordingly, a larger smoother cavity is desirable in vertebroplasty.
A number of patents discuss creating a space or cavity in the vertebral body for certain diagnostic and therapeutic procedures such as a procedure for fixing a bone fracture. U.S. Pat. No. 4,969,888 issued to Scholten et al. describes a method for fixation of osteoporotic bone comprising drilling the osteoporotic bone to form a cavity, followed by inflating an inflatable device inserted into the cavity. Expansion of the inflatable device compacts the bone and is stated to restore the bone height. A flowable synthetic bone material is directed into the cavity and allowed to set to a hardened condition.
U.S. Pat. No. 6,440,138 issued to Reiley (the “Reiley patent”) describes another device and method for creating cavities in an interior body region such as cancellous bone. According to the Reiley patent, various tools carry structures that cut cancellous bone to form the cavity. The cutting structures include filaments in the form of a loop, or brush, a blade that may be moved laterally or rotatetively or both. Also, the structure may comprise a transmitter of energy. The Reiley patent at column 8, lines 19-30, indicates that the type of energy that the transmitter propagates to remove tissue can vary. Described examples include ultrasonic energy and laser energy at a suitable tissue cutting frequency.
A number of patents describe instruments and methods for treating tumors by applying energy from a radio frequency source. See, for example, U.S. Pat. No. 6,622,731 to Daniel.
Although the above described techniques are available, each technique has associated shortcomings. For instance, drilling and compacting the osteoporotic bone fails to remove the bone fragments. The compacted fragments provide an unstable surface for the bone cement to adhere to. The bone fragments may be reabsorbed by the bone body, leaving a void which may facilitate spinal collapse.
Additionally, inserting, expanding and deflating an inflatable member requires additional time and steps. A balloon also does not remove tissue. It compacts the tissue, leaving dead tissue within the bone body. The eventual reabsorbing of tissue leaves a void in the bone body and consequently, the patient may continue to be vulnerable to spinal collapse.
Treating tumors with heat generated from RF energy can also fail to immediately remove the tissue. As the necrotic tissue is reabsorbed, a void develops in the bone body. Such voids lead to spinal collapse.
Accordingly, a fast minimally invasive procedure and apparatus for treating bone disease of an osteoportic and non-osteoporotic origin is still desired.